From KidsHealth.org:
A federal law, the Children's Online Privacy Protection Act (COPPA), was created to help protect kids online. It's designed to keep anyone from obtaining a child's personal information without a parent knowing about it and agreeing to it first.
COPPA requires websites to explain their privacy policies on the site and get parental consent before collecting or using a child's personal information, such as a name, address, phone number, or Social Security number. The law also prohibits a site from requiring a child to provide more personal information than necessary to play a game or participate in a contest.
But even with this law, your kids' best online protection is you. By talking to them about potential online dangers and monitoring their computer use, you'll help them surf the Internet safely.